Isaac Polak was a son of David Polak and Rachel van West. He married Anna Boas in Amsterdam on 2 May 1928, a daughter of Elias Boas and Elisabeth Engelander.
City Archive of Amsterdam, archive card of David Polak and website www.wiewaswie.nl .
In addition, a Jokos file (number 51234) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.